SiC (silicon carbide) has been expected as a material for next-generation semiconductor devices. SiC has excellent properties: bandgap which is three times as large; breakdown field strength which is about ten times as high; and thermal conductivity which is about three times as high, as compared with Si (silicon). The utilization of the characteristics can achieve semiconductor devices that are low in loss and able to operate at high temperatures.
In order to improve characteristics of SiC semiconductor devices, the reduction in contact resistance is desired for metallic electrodes provided on n-type impurity layers. The reduction in contact resistance, for example, for backside electrodes of vertical semiconductor devices is important from the perspective of reducing the ON resistances of the devices.
However, as compared with Si, SiC has smaller potential energy at the lower end of the conduction band. For this reason, as compared with cases of Si, it is difficult to form low contact-resistance metallic electrodes since there is no metallic materials which have such a work function that lowers the barrier between the electrodes and n-type impurity layers and is excellent in oxidation resistance.